1. Field of the Invention
The present invention relates to an image forming apparatus, and in particular, relates to an image forming apparatus that fixes a coloring material-containing ink on a medium through reaction between the ink and a treatment liquid, so as to form a desired image on the medium.
2. Description of the Related Art
In recent years, inkjet recording apparatuses have become widespread as image forming apparatuses for forming images such as pictures and documents on media. An inkjet recording apparatus forms a desired image on a medium by ejecting ink droplets onto the medium from nozzles in heads while moving the heads relatively to the recording medium.
Depending on the type of the medium and the types of the inks, a phenomenon of deposition interference may occur in which an ejected ink droplet overlaps (contacts) at least part of another ink droplet already on the medium, whereby the ink droplets become mixed together. Moreover, if the deposited ink penetrates into the medium, then smearing or spreading out of the dots formed may occur. To prevent image degradation due to such deposition interference and so on, an inkjet recording apparatus has been. proposed according to which ink and a treatment liquid that can react with the ink are deposited onto a medium, and the ink and the treatment liquid are made to react with one another on the medium, whereby deposition interference of the ink, and the like, are prevented (see, for example, Japanese Patent Application Publication No. 8-72234).
Moreover, an inkjet recording apparatus has been proposed in which an ultraviolet radiation-curable ink is used. After the ink has been deposited onto a medium, the ultraviolet radiation-curable ink is irradiated with ultraviolet radiation, whereby the ink is cured and fixed (see, for example, Japanese Patent Application Publication No. 60-132767, and Japanese Patent Application Publication No. 2003-127517).
However, with a system in question two liquids, i.e. an ink and a treatment liquid, are mixed together, as described in Japanese Patent Application Publication No. 8-72234, if the mixing between the two liquids is insufficient or the balance between the two liquids is poor in places, then the curing of the mixture of the two liquids may be insufficient, and hence there is a possibility that the ink is not fixed on the medium.
Moreover, with a system in which an ultraviolet radiation-curable ink is used, as described in Japanese Patent Application Publication No. 60-132767 or Japanese Patent Application Publication No. 2003-127517, there is a possibility that deposition interference of the ink, or the like, may occur before the irradiation of the ultraviolet radiation is carried out, resulting in degradation of the image quality.